Javascript:SpiderMonkey:ProjectGenerationGarbageCollection: Difference between revisions

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Wiki conversion of original Google Document: https://docs.google.com/a/jamsni.com/document/d/1-GZ8F0ZabvdpCnRQaecId0yuu4QFYr5pAvnRC_KFchc/edit
{{outdated}}


<p>Wiki conversion of original Google Document: https://docs.google.com/a/jamsni.com/document/d/1-GZ8F0ZabvdpCnRQaecId0yuu4QFYr5pAvnRC_KFchc/edit
</p>


== Objective ==
== Objective ==
Implement Generational Garbage collection in Spider Monkey. <Some goal based off V8 performance delta % on Earley Boyer benchmark>
<p>Implement Generational Garbage collection in Spider Monkey. &lt;Some goal based off V8 performance delta&#160;% on Earley Boyer benchmark&gt;</p>
<b>Accountable</b>: Naveed<br />
<b>Responsible</b>: Terrence, Steve, Jon, Nicholas, evilpie and Ms2ger<br />
<b>Consulted</b>: bhackett billm<br />
<b>Informed</b>: Product Marketing<br />
<br/>
<b>Tracking Bug:</b> [meta] Implement generational garbage collection - <span class="fck_mw_template"><span class="fck_mw_template"><span class="fck_mw_template">{{bug|619558}}</span></span></span>


* Accountable: Naveed
== Milestones ==


* Responsible: Terrence, Steve, Jon, Nicholas, and evilpie Ms2ger
=== Endgame schedule ===


* Consulted: bhackett billm
* Burndown of rooting hazards and unsafe references: https://people.mozilla.com/~sfink/analysis
* Burndown of bugs blocking Exact Rooting: [https://metrics.mozilla.com/bugzilla-analysis/Dashboard-FinalBurndown.html#esfilter=%257B%22or%22%3A%255B%0A%09%257B%22term%22%3A%257B%22bug_id%22%3A753203%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A745742%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A773686%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A789551%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A791022%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A906940%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A813244%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A848151%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A831379%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A868799%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A877658%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A884617%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898220%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898606%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A791062%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A834909%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A831409%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898554%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A901731%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898970%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A864785%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A868483%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A877699%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898815%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A900144%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A899251%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A899251%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A900998%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A898608%257D%257D,%0A%09%257B%22term%22%3A%257B%22blocked_by%22%3A900713%257D%257D%0A%255D%257D&forTitle=Exact+Rooting&dueDate=2013-10-22&sampleMin=2013-08-01 https://metrics.mozilla.com/...]


* Informed: Product Marketing
{| class="wikitable"
! Milestone
! Bug
! Old Estimated Date
! Current Estimated Date
! Actual Date
! Nightly Version
|-
| ...
|
|
|
|
|-
| style="background:#def;" | [[RapidRelease/Calendar|Nightly 26 (B2G 1.2) is uplifted to Aurora]]
| style="background:#def;" |
| style="background:#def;" | 2013-09-16
| style="background:#def;" |
| style="background:#def;" |
| style="background:#def;" |
|-
| All unsafe references found by static analysis have been fixed
| [https://bugzilla.mozilla.org/show_bug.cgi?id=898608 898608]
| 2013-09-23
| 2013-10-02
|
| 27
|-
| Static analysis of unsafe references is unhidden on TBPL
| [https://bugzilla.mozilla.org/show_bug.cgi?id=834909 834909]
| 2013-09-25
| 2013-10-03
|
| 27
|-
| All rooting hazards found by static analysis have been fixed
| [https://bugzilla.mozilla.org/show_bug.cgi?id=898606 898606]
| 2013-10-18
| 2013-10-07
|
| 27
|-
| Static analysis of rooting hazards is unhidden on TBPL
| [https://bugzilla.mozilla.org/show_bug.cgi?id=834909 834909]
| 2013-10-22
| 2013-10-08
|
| 27
|-
| style="background:#def;" | [[RapidRelease/Calendar|Nightly 27 is uplifted to Aurora]]
| style="background:#def;" |
| style="background:#def;" | 2013-10-28
| style="background:#def;" |
| style="background:#def;" |
| style="background:#def;" |
|-
| ...
|
|
|
|
| 28
|-
| All GGC crashes found by fuzzers have been fixed
| [https://bugzilla.mozilla.org/show_bug.cgi?id=877471 877471]
| 2013-11-__
| 2013-10-__
|
| 28
|-
| AWFY with GGC >= AWFY without GGC
| [https://bugzilla.mozilla.org/show_bug.cgi?id=875863 875863]
| 2013-11-__
|
|
| 28
|-
| GGC is enabled for desktop and Android
| [https://bugzilla.mozilla.org/show_bug.cgi?id=619558 619558]
| 2013-11-__
|
|
| 28
|-
| GGC is enabled for B2G 1.3
| [https://bugzilla.mozilla.org/show_bug.cgi?id=619558 619558]
| 2013-11-__
|
|
| 28
|-
| ...
|
|
|
|
| 28
|-
| style="background:#def;" | [[RapidRelease/Calendar|Nightly 28 (B2G 1.3) is uplifted to Aurora]]
| style="background:#def;" |
| style="background:#def;" | 2013-12-09
| style="background:#def;" |
| style="background:#def;" |
| style="background:#def;" |
|-
| ...
|
|
|
|
| 29
|-
| style="background:#def;" | [[RapidRelease/Calendar|Nightly 29 is uplifted to Aurora]]
| style="background:#def;" |
| style="background:#def;" | 2014-01-20
| style="background:#def;" |
| style="background:#def;" |
| style="background:#def;" |
|-
| ...
|
|
|
|
| 30
|}


Generational GC - {{bug|619558}}
=== Original schedule ===
 
{| class="wikitable"
! Milestone
! Task
! Deliverable
! Assigned
! Estimated Weeks
! Expected Date
! Actual Date
|-
| 1
| Rooting analysis in the shell (x64)
| green on mozilla-inbound
| sfink, jonco, evilpie, Ms2ger
| 2
| 3/7/2013
| 3/2/2013
|-
| 2
| Rooting analysis in the shell (arm)
| green on mozilla-inbound
| sfink
| 2
|
| pending
|-
| 3
| Exactly rooted shell (x64)
| green on mozilla-inbound
| sfink, jonco, evilpie, Ms2ger
| 2
| 3/14/2013
| done?
|-
| 4
| Exactly rooted shell (arm)
| green on mozilla-inbound
| sfink
| 2
|
| pending
|-
| 4.1
| Exactly rooted js/src
| green on mozilla-inbound
| jonco
| 3
| 5/9/2013
| in progress
|-
| 5
| GGC no-jit shell only build on TBPL (x64)
| green on mozilla-inbound
| terrence
| 6
| 2/21/2013
| 4/7/2013
|-
| 6
| GGC no-jit shell only build on TBPL (arm)
| green on mozilla-inbound
| sfink, terrence
| 2
|
| pending
|-
| 7
| JIT support (x64) (Bug 706885)
| TBPL build using JITs and Ion+Baseline+GGC displayed on AWFY
| bhacket
| 8
| 3/15/2013
| 4/7/2013
|-
| 8
| JIT support (arm)
| TBPL build using JITs and Ion+Baseline+GGC displayed on AWFY
| bhacket
| 2
|
| pending
|-
| 9
| Optimized GGC in shell (x64 + arm)
| Ion+GGC faster than Ion-GGC on AWFY
| bhacket
| 12
| 6/1/2013   
| not started
|-
| 10
| Static rooting analysis - browser
| available via mrgiggles and URL
| sfink, bhacket
| 12
| 6/1/2013
| done
|-
| 10.1
| Static analysis on TBPL - browser
| visible on tbpl
| sfink
|
|
| not started           
|-
| 10.2
| Static rooting analysis - b2g
| available via mrgiggles and URL
| sfink
|
|
| pending
|-
| 10.3
| Static analysis on TBPL - b2g
| visible on tbpl
| sfink
|
|
| not started           
|-
| 11
| Exactly rooted browser (x64 + arm)
| green on mozilla-inbound
| sfink, jonco, evilpie, Ms2ger, terrence
| 16
| 7/1/2013   
| in progress
|-
| 12
| GGC in the browser (x64 + arm)
| green on AWFY
| terrence
| 16
| 10/1/2013
| not started
|}


== Steps ==
== Steps ==
Line 19: Line 291:
=== Exact Rooting done in JS Shell {{bug|753203}} ===
=== Exact Rooting done in JS Shell {{bug|753203}} ===


12 weeks started
<p>12 weeks started
 
</p>
* Rooting Analysis on TinderBox (sfink) - done
<ul><li> Dynamic rooting analysis on tbpl (sfink) - done
** Still need to unhide it for inbound - get it green, keep it green
<ul><li> Unhidden on inbound</li></ul>
* Get the root analysis build green - two weeks?
</li><li> Get the root analysis build green - done
** Get jit-tests green {{bug|745742}}
<ul><li> Get jit-tests green <span class="fck_mw_template"><span class="fck_mw_template">{{bug|745742}}</span></span>
** Get js ref tests green  
</li><li> Get js ref tests green  
** Get jsapi-tests green {{bug|831376}}
</li><li> Get jsapi-tests green <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831376}}</span></span>
* Rooting analysis fuzz bugs {{bug|773746}}
</li></ul>
** Rely on static analysis to make this not be a whack-a-mole game
</li><li> Rooting analysis fuzz bugs <span class="fck_mw_template"><span class="fck_mw_template">{{bug|773746}}</span></span>
* Remove E4X - done
<ul><li> Rely on static analysis to make this not be a whack-a-mole game
* Do something about JSD
</li></ul>
* Add exact roots to stack structures - 2 weeks
</li><li> Remove E4X - done
* AddRoot/RemoveRoot for Heap structures - 4 weeks
</li><li> Do something about JSD
* Static code analysis {{bug|831409}}
</li><li> Add exact roots to stack structures - 2 weeks
** Fix all discovered rooting hazards (~800) (sfink,jonco) - 4 weeks
</li><li> AddRoot/RemoveRoot for Heap structures - 4 weeks
** Optimize all discovered over-rooting (~100)
</li><li> Static code analysis <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831409}}</span></span>
** Automate static analysis {{bug|834912}} (sfink)
<ul><li> Fix all discovered rooting hazards (~800) (sfink,jonco) - 4 weeks
*** Need a server (dm-sixgill01?)
</li><li> Optimize all discovered over-rooting (~100)
*** http://people.mozilla.org/~sfink/rootingHazards.txt
</li><li> Automate static analysis <span class="fck_mw_template"><span class="fck_mw_template">{{bug|834912}}</span></span> - done (sfink)
*** http://people.mozilla.org/~bhackett/gcFunctions.html
</li><li> http://people.mozilla.org/~sfink/analysis/browser/rootingHazards.txt
</li><li> http://people.mozilla.org/~sfink/analysis/browser/gcFunctions.txt
</li><li> http://people.mozilla.org/~sfink/analysis/browser/allFunctions.txt
</li></ul>
</li></ul>


=== JIT Integration with post barriers - 4 weeks, parallelized ===
=== JIT Integration with post barriers - 4 weeks, parallelized ===


* IonMonkey {{bug|831506}} - 1 week (bhackett)
<ul><li> IonMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831506}}</span></span> - 1 week (bhackett)
* JaegerMonkey {{bug|764876}} - 2 days (bhackett)
</li><li> JaegerMonkey <span class="fck_mw_template"><span class="fck_mw_template">{{bug|764876}}</span></span> - 2 days (bhackett)
* Baseline JIT {{bug|831507}} - <ask jandem/djvj for an estimate>
</li><li> Baseline JIT <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831507}}</span></span> - &lt;ask jandem/djvj for an estimate&gt;
</li></ul>


=== Generational Garbage Collection in the Shell ===
=== Generational Garbage Collection in the Shell ===


* Implement prototype algorithm (terrence) - 1 week
<ul><li> Implement prototype algorithm (terrence) - 1 week
* This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS|.
</li><li> This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS| - done.
* Re-implement HashTable rekeying
</li><li> Re-implement HashTable rekeying
** We undid this code because it was a perf regression and was still a bit buggy. (terrence) - 3 weeks
<ul><li> We undid this code because it was a perf regression and was still a bit buggy. (terrence) - 3 weeks
** at least part of this is {{bug|726687}}
</li><li> at least part of this is <span class="fck_mw_template"><span class="fck_mw_template">{{bug|726687}}</span></span>
</li></ul>
</li></ul>


=== Exactly Root the Browser {{bug|831379}} - 10 weeks ===
=== Exactly Root the Browser <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831379}}</span></span> - 10 weeks ===


* This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point.
<ul><li> This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point.
</li></ul>


=== Performance Tuning - 4 weeks (This should probably start asap) ===
=== Performance Tuning - 4 weeks (This should probably start asap) ===


* Implement a Nursery {{bug|706885}} - 1 week
<ul><li> Implement a Nursery <span class="fck_mw_template"><span class="fck_mw_template">{{bug|706885}}</span></span> - 1 week
* Test against V8 Earley-Boyer benchmark.
</li><li> Test against V8 Earley-Boyer benchmark.
** Also v8 deltablue, raytrace
<ul><li> Also v8 deltablue, raytrace
* We may need to Implement Bill’s Pools/Zones idea to get the nursery to the requisite perf {{bug|759585}} - 6 weeks
</li></ul>
* Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable - ??? weeks (start early) (bhackett)
</li><li> We may need to Implement Bill’s Pools/Zones idea to get the nursery to the requisite perf <span class="fck_mw_template"><span class="fck_mw_template">{{bug|759585}}</span></span> - 6 weeks - done
</li><li> Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable <span class="fck_mw_template"><span class="fck_mw_template">{{bug|831886}}</span></span> (bhackett) - done
</li></ul>


=== Make the Post Barrier Verifier Green in the browser {{bug|764882}} ===
=== Make the Post Barrier Verifier Green in the browser <span class="fck_mw_template"><span class="fck_mw_template">{{bug|764882}}</span></span> ===


* Investigate how long it will take to do generational barriers - 1 week
<ul><li> Investigate how long it will take to do generational barriers - 1 week
* We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work.  
</li><li> We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work.  
* Make JS_IsAboutToBeFinalized indirect {{bug|765432}} - 10 weeks
</li><li> Make JS_IsAboutToBeFinalized indirect <span class="fck_mw_template"><span class="fck_mw_template">{{bug|765432}}</span></span> - 10 weeks
</li></ul>


== Other ==
== Other ==


* Should we establish a new benchmark specifically for GGC. (sfink votes yes)
<ul><li> Should we establish a new benchmark specifically for GGC. (sfink votes yes)
** What would it measure? there are multiple goals, e.g. throughput/MMU/pause time
<ul><li> What would it measure? there are multiple goals, e.g. throughput/MMU/pause time
** Should we make it a public benchmark?
</li><li> Should we make it a public benchmark?
** What workloads should we consider?
</li><li> What workloads should we consider?
** compartmental GC very important to us, not necessarily applicable to other implementations
</li><li> compartmental GC very important to us, not necessarily applicable to other implementations
** allocation rate (broken down into live vs garbage), steady behavior vs swapping between allocation + computation modes, etc.
</li><li> allocation rate (broken down into live vs garbage), steady behavior vs swapping between allocation + computation modes, etc.
 
</li></ul>
* How can we keep our advantage on Splay benchmark
</li></ul>
** possible to do with TI --- look at types of objects promoted from nursery to major heap, eventually start allocating them directly in the major heap
<ul><li> How can we keep our advantage on Splay benchmark
 
<ul><li> possible to do with TI --- look at types of objects promoted from nursery to major heap, eventually start allocating them directly in the major heap
* Compacting GC - Revisit in Febuary/March - 1 Month
</li></ul>
** Delayed until exact rooting is fully done. We can add this in if we have time in the schedule that we cannot parallelize.
</li></ul>
<ul><li> Compacting GC - Revisit in Febuary/March - 1 Month
<ul><li> Delayed until exact rooting is fully done. We can add this in if we have time in the schedule that we cannot parallelize.
</li></ul>
</li></ul>


== Risks ==
== Risks ==


* Team is responsible for many top crashers
<ul>
 
<li> Team is responsible for many top crashers</li>
* External rooting API has not been designed  
<li> External rooting API has not been designed</li>
 
<li> GGC algorithm has not been decided on - it may not be faster</li>
* GGC algorithm has not been decided on - it may not be faster
<li> JSD1 exact rooting is lurking</li>
 
</ul>
* JSD1 exact rooting is lurking

Latest revision as of 20:52, 27 April 2021

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Wiki conversion of original Google Document: https://docs.google.com/a/jamsni.com/document/d/1-GZ8F0ZabvdpCnRQaecId0yuu4QFYr5pAvnRC_KFchc/edit

Objective

Implement Generational Garbage collection in Spider Monkey. <Some goal based off V8 performance delta % on Earley Boyer benchmark>

Accountable: Naveed
Responsible: Terrence, Steve, Jon, Nicholas, evilpie and Ms2ger
Consulted: bhackett billm
Informed: Product Marketing

Tracking Bug: [meta] Implement generational garbage collection - bug 619558

Milestones

Endgame schedule

Milestone Bug Old Estimated Date Current Estimated Date Actual Date Nightly Version
...
Nightly 26 (B2G 1.2) is uplifted to Aurora 2013-09-16
All unsafe references found by static analysis have been fixed 898608 2013-09-23 2013-10-02 27
Static analysis of unsafe references is unhidden on TBPL 834909 2013-09-25 2013-10-03 27
All rooting hazards found by static analysis have been fixed 898606 2013-10-18 2013-10-07 27
Static analysis of rooting hazards is unhidden on TBPL 834909 2013-10-22 2013-10-08 27
Nightly 27 is uplifted to Aurora 2013-10-28
... 28
All GGC crashes found by fuzzers have been fixed 877471 2013-11-__ 2013-10-__ 28
AWFY with GGC >= AWFY without GGC 875863 2013-11-__ 28
GGC is enabled for desktop and Android 619558 2013-11-__ 28
GGC is enabled for B2G 1.3 619558 2013-11-__ 28
... 28
Nightly 28 (B2G 1.3) is uplifted to Aurora 2013-12-09
... 29
Nightly 29 is uplifted to Aurora 2014-01-20
... 30

Original schedule

Milestone Task Deliverable Assigned Estimated Weeks Expected Date Actual Date
1 Rooting analysis in the shell (x64) green on mozilla-inbound sfink, jonco, evilpie, Ms2ger 2 3/7/2013 3/2/2013
2 Rooting analysis in the shell (arm) green on mozilla-inbound sfink 2 pending
3 Exactly rooted shell (x64) green on mozilla-inbound sfink, jonco, evilpie, Ms2ger 2 3/14/2013 done?
4 Exactly rooted shell (arm) green on mozilla-inbound sfink 2 pending
4.1 Exactly rooted js/src green on mozilla-inbound jonco 3 5/9/2013 in progress
5 GGC no-jit shell only build on TBPL (x64) green on mozilla-inbound terrence 6 2/21/2013 4/7/2013
6 GGC no-jit shell only build on TBPL (arm) green on mozilla-inbound sfink, terrence 2 pending
7 JIT support (x64) (Bug 706885) TBPL build using JITs and Ion+Baseline+GGC displayed on AWFY bhacket 8 3/15/2013 4/7/2013
8 JIT support (arm) TBPL build using JITs and Ion+Baseline+GGC displayed on AWFY bhacket 2 pending
9 Optimized GGC in shell (x64 + arm) Ion+GGC faster than Ion-GGC on AWFY bhacket 12 6/1/2013 not started
10 Static rooting analysis - browser available via mrgiggles and URL sfink, bhacket 12 6/1/2013 done
10.1 Static analysis on TBPL - browser visible on tbpl sfink not started
10.2 Static rooting analysis - b2g available via mrgiggles and URL sfink pending
10.3 Static analysis on TBPL - b2g visible on tbpl sfink not started
11 Exactly rooted browser (x64 + arm) green on mozilla-inbound sfink, jonco, evilpie, Ms2ger, terrence 16 7/1/2013 in progress
12 GGC in the browser (x64 + arm) green on AWFY terrence 16 10/1/2013 not started

Steps

Exact Rooting done in JS Shell bug 753203

12 weeks started

JIT Integration with post barriers - 4 weeks, parallelized

Generational Garbage Collection in the Shell

  • Implement prototype algorithm (terrence) - 1 week
  • This is a potential milestone: we would need to build it and test it on TBPL similar to how |r| works now -- |GGCJS| - done.
  • Re-implement HashTable rekeying
    • We undid this code because it was a perf regression and was still a bit buggy. (terrence) - 3 weeks
    • at least part of this is bug 726687

Exactly Root the Browser bug 831379 - 10 weeks

  • This is a potential milestone: we would turn on exact rooting for release FF at this point. We would not get a performance boost from this (necessarily), but it would lock in our work to this point.

Performance Tuning - 4 weeks (This should probably start asap)

  • Implement a Nursery bug 706885 - 1 week
  • Test against V8 Earley-Boyer benchmark.
    • Also v8 deltablue, raytrace
  • We may need to Implement Bill’s Pools/Zones idea to get the nursery to the requisite perf bug 759585 - 6 weeks - done
  • Refactor code to avoid rooting on hot paths and keep rooter overhead acceptable bug 831886 (bhackett) - done

Make the Post Barrier Verifier Green in the browser bug 764882

  • Investigate how long it will take to do generational barriers - 1 week
  • We may need to rewrite the maps in xpconnect and the browser in terms of HashTable: this could be a bunch of work.
  • Make JS_IsAboutToBeFinalized indirect bug 765432 - 10 weeks

Other

  • Should we establish a new benchmark specifically for GGC. (sfink votes yes)
    • What would it measure? there are multiple goals, e.g. throughput/MMU/pause time
    • Should we make it a public benchmark?
    • What workloads should we consider?
    • compartmental GC very important to us, not necessarily applicable to other implementations
    • allocation rate (broken down into live vs garbage), steady behavior vs swapping between allocation + computation modes, etc.
  • How can we keep our advantage on Splay benchmark
    • possible to do with TI --- look at types of objects promoted from nursery to major heap, eventually start allocating them directly in the major heap
  • Compacting GC - Revisit in Febuary/March - 1 Month
    • Delayed until exact rooting is fully done. We can add this in if we have time in the schedule that we cannot parallelize.

Risks

  • Team is responsible for many top crashers
  • External rooting API has not been designed
  • GGC algorithm has not been decided on - it may not be faster
  • JSD1 exact rooting is lurking
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